C# MVVM Simple Implementation

IoC.cs

using System;
using System.Collections.Generic;

namespace Mvvm
{
    public class Ioc
    {
        private static Dictionary<Type, object> classes = new Dictionary<Type, object>();
        public static void Register<T>(params object[] parameters) where T : class
        {
            bool added = classes.TryAdd(typeof(T), Activator.CreateInstance(typeof(T), parameters));
            if (!added)
                throw new Exception($"Could not register type '{typeof(T)}'; is it already registered?");
        }

        public static T GetInstance<T>()
        {
            bool exists = classes.TryGetValue(typeof(T), out object cls);
            if (!exists)
                throw new Exception($"No instance of type '{typeof(T)}' registered!");

            return (T)cls;
        }
    }
}

Messenger.cs

using System;
using System.Collections.Generic;

namespace Mvvm
{
    public class Messenger
    {
        private static Dictionary<Type, Action<object>> registrants = new Dictionary<Type, Action<object>>();
        private static readonly object registerLock = new object();
        private static readonly object sendLock = new object();

        public static void Send<T>(T obj) where T : class
        {
            lock (sendLock)
            {
                foreach (var item in registrants)
                {
                    if (item.Key == typeof(T))
                    {
                        item.Value(obj);
                        //break; // remove this to allow multiple recipients
                    }
                }
                
                // alternative to using a loop
                //var set = registrants.First(e => e.Key == typeof(T));
                //set.Value?.Invoke(obj);
            }
        }

        public static void Register<T>(Action<object> act) where T : class
        {
            lock (registerLock)
            {
                registrants.Add(typeof(T), act);
            }
        }
    }
}

RelayCommand.cs

using System;
using System.Windows.Input;

namespace Mvvm
{
    public class RelayCommand : ICommand
    {
        public event EventHandler CanExecuteChanged;

        private Action<object> execute;
        private Func<object, bool> canExecute;

        public RelayCommand(Action<object> ex, Func<object, bool> canEx)
        {
            this.execute = ex;
            this.canExecute = canEx;
        }

        public RelayCommand(Action<object> ex)
        {
            this.execute = ex;
        }

        public bool CanExecute(object parameter)
        {
            if (this.canExecute == null)
                return true;
            if (this.canExecute(parameter) == true)
                return true;
            return false;
        }

        public void Execute(object parameter)
        {
            this.execute?.Invoke(parameter);
        }
    }
}